We recently bought a small home, one of many in this area that were built with 7 1/2 foot ceilings. I'd like to be able to raise the ceiling by removing the existing ceiling joists (there's only an un-floored attic space above) and then either shortening them slightly and moving them up on the roof rafters the necessary distance to give a "normal" 8 foot ceiling, or by removing them and replacing them with collar ties to give a more open ceiling. The problem with the latter approach is that the existing rafters span two rooms, so the center wall would have to also be extended up to the collar ties, thereby giving the room a trapezoidal cross section .

Has anyone encountered this problem, and if so, what solution have you come up with to raise the roof and give the rooms a bit more of a spacious look?

Welcome to the Fourm R W Wood:
It looks like you already understand that the joists hold the ceiling up and the walls from pushing out from the weight of the rafters. I wold go for raising one pair of joists at a time; all the others being left to keep the walls tied in, and I would not want to raise them more than the 6" required to give the full 8' ceiling.
An alternative to that would be to put a supporting wall or beam in from end to end of the house at the top of the rafters. The collar ties put more strain on the rafters and will cause sagging but the full height wall or beam will take all the strain off the rafters. Of course, that will need to be done in stages; extending legs from the center wall to catch the weight before removing the joists. You are correct in saying that all walls would then need to be built up to the rafters; or at least the bed room and bathroom walls. The other walls could be left short to give a more open space. Be aware, this could give a lot of problems with electrical wiring unless you have a basement, and all I have said is based on having 2" X 6" or larger raftes; if it is a truss roof don't touch it.
Please post back and let us know how it works out, maybe even some pictures.
Glenn

Welcome to the Fourm R W Wood:
An alternative to that would be to put a supporting wall or beam in from end to end of the house at the top of the rafters.

I'm not sure what you mean by "at the top of the rafters." There is only one wall that runs the length of the house, and it's directly under the peak of the roof. If you mean extending that wall directly to the peak, I suppose that could be done, thereby giving the two rooms either side of the center wall one high and one low wall. I'm not sure there is adequate support in the basement of that center wall though, and adding it would probabably be difficult since the chimney goes up through the middle of the house.

Quote:

Be aware, this could give a lot of problems with electrical wiring unless you have a basement, and all I have said is based on having 2" X 6" or larger rafters; if it is a truss roof don't touch it.

Neither of these points is an issue.

It'll be awhile before we get to doing this, but I'm trying to formulate plans for the whole house prior to starting anything.

Hello R W:
Yes, I was talking about the Peak of the roof and Yes, it would need a beam and posts in the basement to support it. By the way, what supports the middle wall now? The posts would need 16" squares cut in the basement floor and a footer poured at least 1' deep, with some steel reinforcing. The beam could be steel which would make it smaller. It may be placed on each side of the chimney.
The basement is a blessing because any new wiring can be run up into the walls from there.
If you want to open up some more space, you could use a beam to support part of the peak rather than a full length wall. Just make sure it it supported on double or triple studs on each end and those studs set right over a basemet post. The beam would have limitations of length.
Glenn